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A thought experiment about space and layers of detail
A plastic 2-liter soda bottle is filled with warm air, sealed tightly, and placed in a freezer.
After cooling, the bottle is visibly dented inward.
Same bottle.
Same amount of air.
Smaller internal volume.
That much is uncontroversial.
The interesting part is why the space itself got smaller.
The usual explanation ( and where it stops )
Textbook physics says:
- The air cools
- Molecular motion decreases
- Internal pressure drops
- External pressure pushes the bottle inward
This explains the force.
It does not explain the fate of the volume.
The bottle now encloses less physical space than before.
So the question remains:
What changed, exactly?
Re-framing the problem visually
Instead of air and plastic, imagine this:
- A net floating in the ocean
- Inside the net: a small school of fish
- Outside the net: a much larger school of fish
The net loosely defines a region of space, just like the bottle does.
High “temperature” state
At first:
- The fish inside the net are highly excited
- They dart around rapidly
- They push outward against the net
- The net bulges slightly
The fish inside feel resistance from the net and the fish outside pushing inward.
The system is balanced.
Cooling the system
Now imagine the fish inside gradually calm down.
- Less motion
- Less pushing outward
- Less internal agitation
Nothing leaves the net.
No fish escape.
But the pressure from the outside school remains.
What happens next ( the key step )
As the inside fish calm:
- The outer fish push the net inward
- The net collapses slightly
- Water flows out through the net
The fish stay trapped.
The water does not.
The region enclosed by the net becomes physically smaller.
Mapping the analogy back
| Fish analogy | Bottle experiment |
|---|---|
| Fish | Air molecules |
| Net | Plastic bottle |
| Water | The “empty space” medium |
| Excited fish | Hot gas |
| Calm fish | Cold gas |
The crucial observation:
Something subtle happened here. A part of reality that normally exists in and around matter particles, the part that allows us to speak meaningfully about the volume they occupy and their density, is now missing from the inside of the bottle. Where did it go? If nothing left the bottle, then the interior should still contain the same amount of physical volume, right?
The most logical conclusion is that some of the “inner empty space medium” got pushed out of the bottle, just like the water got pushed out through the net.
This may sound obvious to you or not, but it should make you think: What properties do we truly attribute to the “nothingness” between particles? Is this “space” just “nothing” and no questions should be asked of it, or is this empty space actually something and we need to account for?
If we assume that the empty space between the matter particles is actually it’s own medium, then the observed behavior becomes straightforward to understand.
So where did the volume go?
It wasn’t destroyed.
It didn’t slip into an alternate dimension or reality.
It was displaced.
